Feedback antenna system



1949 G. T. ROYDEN 2,480,164

FEEDBACK ANTENNA SYSTEM Filed April 9, 1945 2 Sheets-Sheet 1 IN V EN TOR.

ATTOR EY Patented Aug. 30, 1949 UMTED STATES EATENT 1 This inventiog relates tq g, directive antenna gSy'st especially to a 16w rr'e- ;Ve gqtem g'eystem and an effi-cient gener a lt the {gut/ 51 for "excitihg the nve t ee He mite the us of he Sam quencles at several sta'ticris W ithgut egces'sive'inmime and th l ws e 1. .Q a number of I off an iuverted amfrls nls y' Stabi a i n an a Q in it? 5 8 impedance, nbivel cojribiu'aticn' and 'fatlirl llfi n'at i y me .i vention diagram flfi tctq cf 1 t9 a l tsQIL na a wit? 9. n. m ua ze t e madame 0f inductor 8 and the Leakage yeac talgcg of the two a ves 9 ucto 1-" fiei e ael l symm ha bf ,he t'Q antenna u e Q S in @ebh' t e wi 6 9 an'd't c e t n one wir s in 121135? li 'u m i tinthe Qth w i'i this m nner th @mnw of th WW? 'creaes as it ipbrdaches the end rtug pg ggt EEQEfiPEQ 1.9-

he mt fi Putti .sws rtt b d? 1 2 a vo ta matt Fa pa a? d be e e u te tha the i tcmt lq ntai m capacit r 1. .5 an ind a ztq I3 is a res nance to the d s e .Qp natin fet equenciy.

,since the rid is gnounded, the volta aqm s capacitor 25 also constitu es the we xczi t z 191tage between grid and cathode of vacuum tube I. Thisyoltag'e appearingifrnm ,c'athdd to ground across capacitor 25 is"in phase with'the vcltage existing acrcssithe ldad circuit of Vacuum tube 1 with respect to ground because the vacuum tube atct's' asambnfirf"Thus fiart pf'th pg-wet reciifiedqift'lf 'tralimTSin fin' will be 1?;

excitation of vacuum tube and the remainder will be returned to the load circuit.

In this manner the power which would ordinarily be dissipated in the impedance matching resistor at the terminal of the directive antenna is utilized. A further advantage of this system is that, because of the power returned to the circuit, the power is higher than would otherwise be produced in the vacuum tube I.

The frequency of operation is determined partly by the resonant circuits constituted by inductor 4 and capacitor 5 also inductor I3 and capacitor 25, but principally by the total length of the transmission path extending through the antenna to the far end and back through the transmission line to the input circuit of vacuum tube The precise frequency will be such that the voltage arriving at the grid with respect to the cathode will be 180 electrical degrees out of phase with the voltage in the anode circuit of vacuum tube with respect to ground.

In Fig. 2 in addition to the elements previously described, an artificial line is shown comprising capacitors l5 and H and inductor l8. One or more of the elements of this artificial line may be made variable. They serve to change the equivalent electrical length of this line and to adjust the operating frequency.

Fig. 2 also provides a grid capacitor I9 and a grid leak resistor 20. tains inductors 2| and 22, by-passed by capacitors 23 and 24. Capacitor 25 serves to resonate inductors 2| and 22. Capacitor 28 neutralizes the reactance of inductor I3.

A series of capacitors 29, 30, 3|, 32, 33, 34

means for changing the characteristics of the antenna so that the apparent velocity of propagation of the current flowing towards inductor l0 can be made equal to the velocity of propagation of the radiated wave. This improves the transfer of power from the antenna to the radiated -l.

wave.

Fig. 3 shows a system for frequency modulation. Inductor coil [8 in the artificial line is coupled to another inductor coil 4|. This latter coil is in the plate circuit of a modulator vacuum tube 42 the grid circuit of which is controlled by the signal intelligence to be transmitted. Variations in the voltage impressed on the grid circuit of vacuum tube 42 cause a change in impedance shunted across inductor 4|. flectedby a change in reactance of coil 8 and consequently a variation in the frequency of oscillation.

Two or more antennae similar to those described may be employed for the purpose of obtaining a better directional radiation pattern. This is schematically explained in Fig. 4. Local auxiliary antenna 43 is so located that its maximum radiation is in the direction of local receiving station (not shown) intended for reception of signals on the same frequency from another local source 44. Phase and magnitude of the current supplied to antenna 43 from source 46 should be so adjusted that the radiation from this antenna counter-balances the radiation from the main antenna 45 in the direction of the receiving station.

Alternatively, the two antennae 43, 45 can be The cathode circuit con- This change is rephase shifting or phase balancing device 48 arranged between source 41 and antenna 43 as indicated in Fig. 4, in dotted lines.

Other variations may be made by one skilled in the art without exceeding the scope of this invention.

What I claim is:

1. In combination, an antenna system, an amplifier including a cathode circuit and a plate T tank circuit, said antenna system substantially radiant acting to energy received from said plate tank circuit, said cathode circuit coupled to receive the energy not radiated by said radiant acting antenna system and returned back over said radiant acting antenna system to provide said amplifier with regenerative energy.

2. A system according to claim 1, wherein said amplifier has a grounded grid.

3. A system according to claim 1, wherein said antenna system comprises a closed transmission line including an input impedance connected to the plate tank circuit and a terminating impedance coupled to ground, the amount of coupling being such that the terminating impedance when reflected through the coupled circuits will be substantially equal to the surge impedance of the transmission line.

4. In a system according to claim 1, an antenna system comprising at least a pair of antenna wires elevated above ground, a first inductance having ends connected to one end of said antenna wires and having a center connection to the plate tank circuit, a second inductance connected to the other end of said antenna wires and inductively coupled to ground, the amount of coupling being such that the terminating impedance when reflected through the coupled circuit will be equal to the surge impedance of the transmission'line formed by said antenna wires.

5. In a system according to claim 1, an antenna system comprising at least a pair of antenna wires elevated above ground, a first inductance having ends connected to one end of said antenna wires and having a center connection to the plate tank circuit, said center connection forming two halves of said first inductance, a second inductance connected to the other end of said antenna wires and inductively coupled to ground, the amount of inductive coupling of said second inductance being such that the terminating impedance when reflected through the coupled circuit will be equal to the surge impedance of the transmission line formed by said antenna wires, said inductive coupling including a third inductance connected to ground, and means including a capacitance for neutralizing the reactance of said third inductance and of the leakage reactance of the two halves of said first inductance.

6. In a system according to claim 1, a cathode circuit tuned at resonance with the operating frequency of said antenna system.

7. In a system according to claim 1, an amplifier consisting of a vacuum tube triode, means for operating saidtriode inversely, said means including a control grid for said triode connected to ground, input and anode circuits for said triode, resonant circuits included in said input and anode circuits and determining the frequency of operation together with the total length of the transmission path extending through said antenna system to the far end and back to the input circuit, the voltage arriving at the control grid being 180 electric degrees out of phase with the voltage in the anode circuit.

8. In a system according to claim 1. an antenna system forming an artificial line and variable elements for changing the equivalent electrical length of said artificial line to adjust the operating frequency.

9. In a system according to claim 1, a cathode circuit including inductors by-passed by capacitors for resonating said inductors and neutralizing the reactance of the coupling.

10. A system according to claim 1, an antenna system comprising a closed transmission line including an input impedance connected to the plate tank circuit and a terminating impedance coupled to ground, the amount of coupling being such that the terminating impedance when reflected through the coupled circuits will be substantially equal to the surge impedance of the transmission line, said transmission line comprising means for changing the characteristics of said antenna system so that the apparent velocity of propagation of the curr nt flowing towards said input inductance is made substantially equal to the velocity of propagation of the radiated wave.

11. In a system according to claim 1, a cathode circuit inductively coupled to said antenna system and forming therewith an artificial line.

12. In a system according to claim 1, a cathode circuit inductively coupled to said antenna system and forming therewith an artificial line, and modulating means coupled to said artificial line.

13. In a system according to claim 1, a cathode circuit inductively coupled to said antenna system and forming therewith an artificial line, a first inductance in said artificial line, a second inductance coupled to said first inductance, a

modulator tube having a plate circuit coupled to said second inductance and having a grid circuit controlled by signal intelligence to be transmitted so as to cause a change in impedance shunted across said second inductor said change being accompanied by a change in reactance of said first inductance and a modulation in the frequency of oscillation.

14. In an antenna system of the type in which the antenna serves as a frequency determining transmission line element in the feedback circuit of an oscillator; the combination of means coupling said oscillator to said antenna to provide a radiating wave traveling over said antenna and terminating coupling means for said antenna for feeding back the unradiated portion of said Wave over said antenna to said oscillator.

15. An antenna system comprising an amplifier, a two conductor antenna, means for coupling the output of said amplifier to said antenna in such energy transfer relation that current flow is in the same direction in said conductors, and terminating means for returning energy to the input of said amplifier in such relation that current flow is in opposite directions in said conductors.

GEORGE T. ROYDEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'IENTS 39 Number Name Date 1,986,623 Conklin et al Jan. 1, 1935 2,237,765 Moser Apr. 3, 1941 2,262,932 Guanella NOV. 18, 1941 r 2,290,314 Carter July 21, 1942 0 2,297,925 Usselman Oct. 6, 1942 2,393,656 Royden Jan. 29, 1946 2,396,884 Robinson Mar. 19, 1946 

